CBSE BoardEnglish MediumSTD 10ScienceElectricity2 Marks
Question
How does the resistance of an ohmic conductor depend on the applied voltage?
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Answer
Ideally it does not depend on the applied voltage. However, when a voltage is applied across an ohmic conductor, some current will flow through it. Due to the current, the temperature of the conductor will rise. As most conductors have a positive temperature coefficient of resistance, the resistance of the conductor will increase according to the following relation.
$R=R_{\text {ref }}\left[1+a\left(T-T_{\text {ref }}\right)\right]$
Where
$R =$ Conductor resistance at temperture "T"
$R _{ ref }=$ Conductor resistance at reference temperature.
$T_{\text {ref, }}$ usually $20^{\circ} C$, but sometimes $0^{\circ} C$.
\$lalpha\$ = Temperature cofficient of resistance for the conductor material.
$T_{\text {ref }}=$ Reference temperature that a is specified at for the conductor material.
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